@Tim Edwards HELLO i have been working in my design its 5v device and 1.8v device i am grounding seprately one of them is g1 and other is g2 but its getting shorted could you please say how to to make it seprate

@Rafeeq Khan Mohammed the first method is to surround one region with

isosubstrate

.

vssa1

and

vssd1

will be still connected through high resistance psubstrate, but often that is not considered a problem. Sometimes, if there are concerns about noise, one region will be placed over a deep nwell. In this case,

vssa1

will be electrically isolated from

vssd1

.

@Mitch Bailey the whole device is over deep nwell. But still it's shorted Main concern is to separate them for the sake of noise in caravel part analog ground and digital ground separation This are auto generated devices You mean 1.8 device with nwell and 5v devices deepnwell ? if that's so I will cross verify that it is I am guessing both are deepnwell For 1.8 devices p substrate is used where as 5v mv p substrate is used

@Rafeeq Khan Mohammed: In deep nwell, it will only be electrically separated if surrounded by nwell.

@Tim Edwards that means I need to surround nwell for 5v devices? Or It's Okay that making sure that 1.8 devices are with n well only not with deep well and 5v devices with deep well Whether both the above methods works to make electrically separate? Surround mean that I just need to paint borders nwell not on the device? Thank you

It is not clear to me from the SkyWater DRC rules whether it is legal to put a 1.8V device in a pwell inside an HV nwell. It is probably safer to keep the 1.8V device outside of the deep nwell or in its own separate deep nwell region.

@Rafeeq Khan Mohammed in order to isolate the pwell region inside deep nwell, the border of the deep nwell region must overlap nwell. See https://www.planetanalog.com/using-deep-n-wells-in-analog-design/ It’s missing a top view, which would show the nwell guard ring around the entire edge of deep nwell.

@Tim Edwards @Mitch Bailey Thank you so much

@Rafeeq Khan Mohammed I’m not that familiar with magic layers to tell, but I don’t think you have any nwel taps.

@Mitch Bailey okay thank you